use action, not sideAction

sideAction is for things not generally related to the current action being
performed. And, it adds a newline after the side action. This was not the
right thing to use for stuff like "checksum", where doing a checksum is
part of the git annex get process, and indeed we want it to display
"(checksum...) ok"

Backend/Hash.hs

@@ -116,7 +116,7 @@ checkKeyChecksum hash key file = go `catchHardwareFault` hwfault
 		case (mstat, fast) of
 			(Just stat, False) -> do
 				filesize <- liftIO $ getFileSize' file stat
-				showSideAction "checksum"
+				showAction "checksum"
 				check <$> hashFile hash file filesize
 			_ -> return True
 	expected = keyHash key